Prior art fuse-plugs have been of the adapter-type and have all required the disassemblying of the housing in order to remove a burned-out fuse, some requiring a replacement of the entire contact element serving as the male prong. Typical of these patents are U.S. Pat. No. 2,849,573 which has a fuse-portion integrally mounted non-removably between male and female elements for each prong. Also each element of the prongs of the U.S. Pat. No. 3,833,875 has its own separate fuse, each fuse being non-removable except by disassembling the entire housing. Likewise the fuses are non-removably enclosed, requiring a removal of a screw to disassemble the housing for the U.S. Pat. No. 3,497,850, and likewise for U.S. Pat. No. 3,184,569. None of the patents relate to features of replacement devoid of disassembling, nor with easily removable fuse-feature tempered with safety features. Likewise, none of these prior art patents relate to Christmas-tree lights which are notoreous in their inherent dangers of short-circuitry and tree fires involving short circuits.